any wave/surf science experts out there ?
Are you speaking hypothetically Brendo, or is this actually going to happen?
Surely a ship can't be scuttled in such shallow water?
for real !! Just google HMAS Adelaide and you'll find the info. It's happening on March 27.
You can even go on a Bass & Flinders Tour to watch it being scuttled. Nice for the local divers I guess.
we would love one of those down this way. Only we would prefer it to be lying on its side, just below the surface, about 100m offshore.
We really need some good solid banks.
Some years back there was a movement to get one of those sandbag reefs put in, but it seems that the interest washed away with the tide. I don't think they work all that well anyway.
Anyone have a spare old warship lying around that they aren't using?
I am not an expert, but have read some things on this subject in the past. from my understanding, the actions that cause a wave to break on the beach are only a few metres deep. otherwise you would have waves breaking way out to sea in much deeper water.
So it is unlikely to affect the waves breaking on the beach too much.
How far off the shore will it be scuttled? If it is in close there may be a build up of sand in the protected side of the ship, which long term would affect how the beach forms sand banks.
If it is scuttled well away from the shoreline then I would say that things wont really change.
If there are any Coastal Geomorphologists out there, then feel free to correct me.
Sure, waves only break once they reach a certain threshold regarding the size of the swell and the water depth but most swells 'feel' the bottom and this is what Brendo is getting at I think.
Will this submerged ship slow down approaching swells at that point and possibly amplify wave heights into a certain part of the beach or create a peaky wedge like setup.
Without doing comprehensive and high resolution modelling I would say it would be too hard to guess what affect the ship will have.
But I'm sure Brendo will be keeping a close eye on proceedings!
Yep, from what I know, the depth of a wave is about half the fetch, so if the waves are coming through anywhere from 50m apart in deep water, then the ship on a 32m deep sand bed will definitely "feel" the swell. Some say it will, experts can't agree and it's probably impossible to really tell what will happen until it's actually down there.
When a swell feels the bottom (in this case the ship) it slows down.
This means the swell energy either side moves in front of the slowed down area concentrating the swell over the shallow area causing a peak.
How much this happens depends on the depth of the ship relative to the swell size and wave period.
Bit of background first - the sinking of ex HMAS Adelaide off Avoca beach. In 30-35 metre deep water, bow facing SE direction, 135m long. The tops of it will be about 10m under the surface depending on tide and how much it settles in to the sand which is about 5m thick at the bottom. The bay at Avoca is about 2 - 2.5 km wide from Sth Avoca to the Skillion in the North. Sand bottom basically in the centre of the beach extending outwards and rock bottoms at both North and South off the points.
What I want to know is, how will this effect the waves at Avoca? Obviously a NE/E swell would pump right through in to Avoca and this boat would be right in the wave path (and S/SE swell would go right past the bay and not affect waves there). So under 'normal' conditions how would the average 1m rideable wave at Avoca be changed due to this boat being out there?
Any help, in laymans terms would be appreciated. Cheers.